The invention relates to an apparatus for continuously measuring the liquid level in a container, particularly a fuel tank of a motor vehicle, having a sensor such as a flexible, multiple-strand band or strap type cable arranged on a mount, with the cable being the oscillation-determining element of an oscillator, the output of which communicates with a control and/or display stage.
In known apparatus of this type, the end of the sensor toward the floor of the container is provided with a bridge which connects the individual strands of the cable, and this end is connected with a rod secured on the mount, in order to reliably prevent a movement of the end of the sensor which might influence the indication of liquid level. In this manner, the effective portion of the sensor ends at a distance above the container floor, as determined by these attachment and connection devices, so that when the container is empty a residual quantity remains in the container that is not detected with the sensor. This residual quantity is also not constant in containers of similar construction, but changes from container to container on the basis of common manufacturing tolerances. Particularly in flat containers with large volume capacity, it can occur that the floor of the container plastically deforms over time under the weight of the fuel acting thereon when the container is full, thus bulging downward. In this manner, there is a further increase over time of the fuel volume not detected with the measurement apparatus.
Particularly in those arrangements wherein a display is desired of the distance which can be yet driven with the fuel supply present in the fuel tank when a certain manner of driving is maintained, it is an absolute requirement that the quantity of fuel in the fuel tank, and particularly the residual quantity, is determined precisely, because otherwise a too large or too small distance will be displayed.